package com.atguigu.nio.groupchat;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.*;
import java.util.Iterator;

public class GroupChatServer {
    private Selector selector;

    private ServerSocketChannel listenChannel;

    private static final int PORT = 6667;

    //初始化工作
    public GroupChatServer(){
        try {
            selector = Selector.open();
            listenChannel = ServerSocketChannel.open();
            listenChannel.socket().bind(new InetSocketAddress(PORT));
            listenChannel.configureBlocking(false);
            listenChannel.register(selector, SelectionKey.OP_ACCEPT);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void listen(){
        try{
            //循环处理
            while (true) {
                int count = selector.select();
                if (count > 0) {
                    Iterator<SelectionKey> iterator = selector.selectedKeys().iterator();
                    while (iterator.hasNext()) {
                        SelectionKey key = iterator.next();
                        if (key.isAcceptable()) {
                            SocketChannel sc = listenChannel.accept();
                            sc.configureBlocking(false);
                            sc.register(selector, SelectionKey.OP_READ);
                            System.out.println(sc.getRemoteAddress() + "上线");
                        }
                        if (key.isReadable()) {
                            readData(key);
                        }
                        iterator.remove();
                    }
                } else {
                    System.out.println("等待...");
                }
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            //发生异常处理
        }
    }

    //读取客户端消息
    private void readData(SelectionKey key){
        SocketChannel channel = null;
        try{
            channel = (SocketChannel) key.channel();
            ByteBuffer buffer = ByteBuffer.allocate(1024);
            int count = channel.read(buffer);
            if(count>0){
                String msg = new String(buffer.array());
                System.out.println("form 客户端："+msg);
                sendInfoToOtherClients(msg,channel);
            }
        } catch (IOException e) {
            try{
                System.out.println(channel.getRemoteAddress()+"离线了..");
                key.cancel();
                channel.close();
            } catch (IOException ex) {
                ex.printStackTrace();
            }
        }
    }

    private void sendInfoToOtherClients(String msg, SocketChannel self) throws IOException {
        System.out.println("服务器转发消息中...");
        for (SelectionKey key : selector.keys()) {
            Channel targetChannel = key.channel();
            if (targetChannel instanceof SocketChannel && targetChannel != self) {
                SocketChannel dest = (SocketChannel) targetChannel;
                ByteBuffer buffer = ByteBuffer.wrap(msg.getBytes());
                dest.write(buffer);
            }
        }
    }

    public static void main(String[] args) {
        GroupChatServer groupChatServer = new GroupChatServer();
        groupChatServer.listen();
    }
}
